Nanostructure and thermomechanical properties of Si3N4/SiC composites fabricated from Si-C-N precursor powders.

Niihara, Koichi; Hirano, Tomoyuki; Nakahira, Atsushi; Suganuma, K.; Izaki, Kansei; Kawakami, T.

doi:10.2497/jjspm.36.243

Cited by 25 publications

(10 citation statements)

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“…Research showed that reaction (6) was not thermodynamically favored in the carbothermal process. 43 The particle shape and size of the SiC powder produced through carbothermal reduction of silica are determined by the starting carbon particles, which supports the fact that SiC is formed via reaction (5).…”

Section: Resultsmentioning

confidence: 99%

“…To obtain high‐quality final products, the SiC nanoparticles must be uniformly dispersed in the composite powder. The methods reported for the fabrication of the nanocomposite powders have included chemical vapor deposition 6 from or pyrolysis 4,7 of organic precursors (to make amorphous Si–N–C powders, which crystallize into Si 3 N 4 /SiC nanocomposites during sintering), mechanical mixing of a Si 3 N 4 micro/nanopowder with a SiC nanopowder 8 or an Si–N–C amorphous powder, 9 adding carbon to a Si 3 N 4 powder (SiC nanoparticles are produced in situ during sintering through the reaction between the carbon and the silica located on the surface of the Si 3 N 4 particles), 10,11 partial reaction of a Si 3 N 4 powder with pyrolyzed carbon, 12–14 nitridation of SiC, 15 and carbothermal reaction of a mixture of silica and carbon powders in a nitrogen atmosphere 16,17 . Among these approaches, the use of amorphous Si–N–C powders has achieved the most uniform distribution of SiC, and consequently excellent mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

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Carbothermal Reaction of Silica–Phenol Resin Hybrid Gels to Produce Silicon Nitride/Silicon Carbide Nanocomposite Powders

Riedel

2007

Journal of the American Ceramic Society

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A carbothermal reaction of silica–phenol resin hybrid gels prepared from a two‐step sol–gel process was conducted in atmospheric nitrogen. The gels were first pyrolyzed into homogeneous silica–carbon mixtures during heating and subsequently underwent a carbothermal reaction at higher temperatures. Using a gel‐derived precursor with a C/SiO2 molar ratio higher than 3.0, Si3N4/SiC nanocomposite powders were produced at 1500°–1550°C, above the Si3N4–SiC boundary temperature. The predominant phase was Si3N4 at 1500°C, and SiC at 1550°C. The Si3N4 and SiC phase contents were adjustable by varying the temperature in this narrow range. The phase contents could also be adjusted by changing the starting carbon contents, or by its combination with varying reaction temperature. A two‐stage process, i.e., a reaction first at 1550°C and then at 1500°C, offered another means of simple and effective control of the phase composition: the Si3N4 and SiC contents varied almost linearly with the variation of the holding time at 1550°C. The SiC was nanosized (∼13 nm, Scherrer method) formed via a solid–gas reaction, while the Si3N4 has two morphologies: elongated microsized crystals and nanosized crystallites, with the former crystallized via a gaseous reaction, and the latter formed via a solid–gas reaction. The addition of a Si3N4 powder as a seed to the starting gel effectively reduced the size of the Si3N4 produced.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Carbothermal Reaction of Silica–Phenol Resin Hybrid Gels to Produce Silicon Nitride/Silicon Carbide Nanocomposite Powders

Riedel

2007

Journal of the American Ceramic Society

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“…Niihara and colleagues [7][8][9][10][11][12][13][14][15] have investigated Si3N4/SiC nanocomposiite, in which the nano-sized SiC particles are dispersed mainly within the matrix grains.…”

Section: Introductionmentioning

confidence: 99%

The Correlation Between Interface Structure and Mechanical Properties for Silicon Nitride Based Nanocomposites

Niihara

Hirano

Nakahira

et al. 1992

Grain Boundary Controlled Properties of Fine Ceramics

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SiaN,,/SiC nanocomposites were prepared by hot-pressing fine, amorphous Si-C-N precursor powders.Transmission electron microscopic observation revealed that the nano-sized SiC particles are dispersed within the matrix grains and/or at the grain boundaries, depending on the volume fraction of the SiC, the size of the SiC particles, and the sintering conditions. The intragranular nano-sized SiC particles affect the growth of elongated SiaN" grains thereby improving fracture toughness and strength. The intergranu-1ar nano-sized SiC particles act to control the grain boundary structure by connecting directly with the matrix SiaN4 grains without the interface layer, thereby improving the high-temperature fracture behavior.in fracture toughness, but a decrease in fracture strength [3,4]. Investigation by Lange [5] of the mechanical properties of SiaN" ceramics containing dispersed SiC particles (average size: 5, 9, 32 /.1. m) showed that the K. Ishizaki et al. (eds.), Grain Boundary Controlled Properties of Fine Ceramics

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“…The first experimental investigations on Si 3 N 4 /SiC nanocomposites were conducted by Niihara's group. 4,5 The approach of forming nanocomposites was later formally introduced by the same group as a new design concept of structural ceramics, 6,7 which contributed to the wave of interest in these materials in the following years.…”

Section: Introductionmentioning

confidence: 99%

The creep behavior of Si3N4/SiC nanocomposites

Wan

Mukherjee

2003

JOM

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a In an investigation of the creep properties of silicon nitride/silicon carbide nanocomposites, the micro-nano type composites with nano-SiC at intragranular and inter-granular regions show behavior not much different from that of silicon-nitride monolith. The improvement of creep resistance is modest, up to about one order of magnitude decrease in steady-state creep rate. The creep rate parameters such as activation energy and stress exponent measured for this type of nanocomposite are within the range of those of silicon nitride. This evidence suggests that a special strengthening mechanism may not be necessary for this type of material. Nano-nanocomposites show remarkably lower creep rates, possibly pointing to a new creep mechanism such as solid-state diffusion.

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Nanostructure and thermomechanical properties of Si3N4/SiC composites fabricated from Si-C-N precursor powders.

Cited by 25 publications

References 0 publications

Carbothermal Reaction of Silica–Phenol Resin Hybrid Gels to Produce Silicon Nitride/Silicon Carbide Nanocomposite Powders

Carbothermal Reaction of Silica–Phenol Resin Hybrid Gels to Produce Silicon Nitride/Silicon Carbide Nanocomposite Powders

The Correlation Between Interface Structure and Mechanical Properties for Silicon Nitride Based Nanocomposites

The creep behavior of Si3N4/SiC nanocomposites

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